pi-openai-reasoning

Change reasoning effort in long Codex conversations without changing the original request effort and needlessly invalidating its cached prefix.

• Uses Pi's existing thinking controls. No new command or provider.
• Keeps effort updates at stable positions across retries, resume, forks and trees.
• Works alone, or with pi-fast, pi-codex-tools and pi-codex-compaction.

Installation

Requires Pi 0.85.1 or later and an existing Pi openai-codex OAuth login.

pi install npm:pi-openai-reasoning

For local development:

pi -e /path/to/pi-mono/packages/pi-openai-reasoning

Installing the package enables this behavior for supported requests. It does not change your selected effort. Use Pi's thinking selector or SDK setThinkingLevel. There is no public OpenAI API support in this first version and no API-key fallback.

Support and limits

The verified model is openai-codex/gpt-6-astra, standard single-agent Responses, with low, medium, high, xhigh or max effort. Other models/providers, Pro mode, backend multi-agent requests, server auto-compaction/truncation, stored conversation references and requests already containing configuration updates are left unchanged. This package does not add async tools or mid-turn steering.

The first request pins the effort for its current context window. Later changes use configuration_update input items before new user input, or after tool history when no new user input exists. All other request fields remain intact. An identical retry retains its previous selection, even if the thinking selector changed meanwhile. The change applies when history advances.

State is reconstructed from the active session branch on every request. It stores efforts, item positions and SHA-256 history fingerprints, not duplicate prompts. After successful compaction, a new request baseline and an explicit effort update after the checkpoint restore the selected effort. Failed compaction cannot change the saved pin. With pi-codex-compaction, direct checkpoint requests also receive the current settings through its versioned public event bus.

If history changes outside normal append/branch/compaction operations, the package starts a new baseline rather than placing an update at an unchecked position. It stops rewriting above 20,000 input items, 16 MiB of serialized history or 128 effort changes in a context window. The byte budget is checked during JSON serialization, including within individual input items. Pi's normal effort handling then remains in use. This can reduce cache reuse; no cache-hit or cost saving is guaranteed. Uninstalling the package leaves normal Pi messages and thinking settings intact.

Protocol reference

The implementation is original Pi code. It was informed by read-only study of openai/codex commit 654b0a77d0d2f81aa21f61caf7af4be88fe550bb (2026-09-11): core/src/session/reasoning_effort.rs, its tests, and RemoteCompactionV2. No Codex code is copied or vendored.

The Codex backend accepted Astra configuration_update values through max in live subscription probes on 2026-09-11 without additional beta headers. The combined Fast + grammar + reasoning + remote-compaction smoke test also passed: the continuation recalled the test word, and Pi recorded compaction usage. Public reasoning documentation describes the input shape, but is not treated as proof of Codex support.

Development and smoke test

npm run -w packages/pi-openai-reasoning check
npm test -w packages/pi-openai-reasoning
npm run -w packages/pi-openai-reasoning pack:dry-run

Tests mock network access. The separate live smoke test uses your existing Codex subscription and consumes usage. It sends short text prompts, changes effort, compacts and checks continuation. It never generates images.

PI_CODEX_LIVE_SMOKE=1 PI_TELEMETRY=0 npm run -w packages/pi-openai-reasoning smoke:live

In the TUI, use the existing thinking selector for low/high, send a short prompt after each change, then /compact and continue. The selector should still show the effective effort. Print, JSON and RPC requests use the same hooks without UI.

Telemetry is best-effort, once per version, with a five-second timeout. Disable it with PI_OFFLINE=1, PI_TELEMETRY=0, or enableInstallTelemetry: false.